/**
 * BinaryExpression.java
 * Copyright (C) 2011 Yuanyan<yuanyan.cao@gmail.com>
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
package edu.rabbit.kernel.schema;

import org.antlr.runtime.tree.CommonTree;

import edu.rabbit.DbException;
import edu.rabbit.schema.IBinaryExpression;
import edu.rabbit.schema.IExpression;

/**
 * @author Yuanyan<yanyan.cao@gmail.com>
 * 
 */
public class BinaryExpression extends Expression implements IBinaryExpression {

    private final Operation operation;
    private final IExpression leftExpression, rightExpression;

    public BinaryExpression(CommonTree ast) throws DbException {
        operation = Operation.decode(ast.getText());
        assert operation != null;
        if (operation == Operation.EQUALS || operation == Operation.NOT_EQUALS) {
            leftExpression = create((CommonTree) ast.getChild(1));
            rightExpression = create((CommonTree) ast.getChild(0));
        } else {
            leftExpression = create((CommonTree) ast.getChild(0));
            rightExpression = create((CommonTree) ast.getChild(1));
        }
    }

    public Operation getOperation() {
        return operation;
    }

    public IExpression getLeftExpression() {
        return leftExpression;
    }

    public IExpression getRightExpression() {
        return rightExpression;
    }

    @Override
    public String toString() {
        StringBuffer buffer = new StringBuffer();
        buffer.append(getLeftExpression());
        buffer.append(' ');
        buffer.append(operation);
        buffer.append(' ');
        buffer.append(getRightExpression());
        return buffer.toString();
    }
}
